9623350 Stratton Plant breeding systems act as filters on the quantity and quality of individual reproduction and influence population genetic structure, demography, and ecology. In turn, both ecological factors and genetic interactions shape the evolution of plant breeding systems. Previous analyses of plant mating system evolution have concentrated on the role of genetic factors and little is known about the role of pollination ecology in mating system evolution. This project fills that gap with experimental comparisons of the reproductive success of selfing and outcrossing plants. Using the polymorphic granite outcrop endemic Arenaria uniflora as a model system, three integrated experiments will be conducted. First the analysis of inbreeding depression in selfing and outcrossing individuals will indicate forces opposing the spread of self-fertile genotypes. Second, paternity analysis using marker alleles will measure the loss of male reproductive success associated with selfing. Third, the value of automatic selfing in conferring reproductive assurance under conditions of pollinator scarcity will be tested experimentally. Findings will provide an integrated analysis of the costs and benefits of each mating strategy under different ecological conditions. This information will be of value in predicting population responses to changes in pollinator abundances under habitat fragmentation or other forms of environmental degradation.
